Alright, thanks for the pointers! Cropping isn’t an issue, since it always resizes the image to a set size. But the horizontal lines do get squished into more of a box shape in the end which could be a problem. Another potential issue with drawing symbols of varying sizes is that the pencil stroke width will be wider/narrower relative to the overall size.
I’ll try a larger training set to try to improve the recognition a bit for this project without having to replace the method entirely since it’s on a strict deadline, but I will make sure to read up on the other classifiers and cnn’s thoroughly and then do a ml course when I have time! 